The present invention relates to a detachable storage device, and, more particularly, to a detachable USB storage device that can be accessed fully by a user of a host computer regardless of the user's access privileges.
A keychain storage device is a detachable module that provide a disk-like storage area on which a user of a host computer can save data, and a USB interface that enables the module to communicate with the host computer. The focus of the present invention is on the means and methods of communications between the storage device and the host computer.
Existing operating systems include support for Mass Storage Class (MSC) USB devices. These devices are meant to provide the user of the host computer with simple storage, much like a hard disk. Standard access to MSC devices can be performed using the host computer's operating system without the need for privileged operation (such as an administrator in Microsoft's Windows operating system). Any special operations not defined under the standard require the use of a private command interface, not available unless in administrator mode. Examples of such special commands include passing a password to a secure storage device and setting the USB device's clock.
For some types of peripheral media, the operating system automatically executes a predefined file stored on the medium when the operating system recognizes that the medium has been connected to the computer. For example, when a data CD is inserted into the CD drive of a Windows system, the operating system finds and executes a file on the CD called “autorun.inf”. With some operating systems, this feature is not available for simple removable storage devices, such as keychain storage devices.
These limitations of the operating system can be overcome by installing, in the host computer, a special device driver for the keychain storage device that allows any type of communications, and includes an automatic execution feature.
Such a device driver requires special development, and installation on all personal computers that the USB memory module is intended to be connected to. Because keychain storage devices are supposed to operate seamlessly on every computer the user works on, this is a major drawback. Furthermore, access of such a device driver also is limited by Windows to users with administrator privileges, for security. Administration privileges are usually not available to users. Even a manager who has administrator privileges in his/her own company is unlikely to be given such privileges in a venue outside that company such as an Internet café.